Evaluating the similarity rules applied to model experiment of large-scale tuna purse seine

Abstract

This study primarily evaluated the effects of different small-scales on the model criteria in theory and proved the feasibility of introducing prototype netting and Tauti's law to construct the large-scale purse seine model net. It was concluded that difference of scale of twine diameter/mesh size will not affect the model law. An experiment of testing with the gear model based on the Tauti's law and sea trial of full-scale fishing gear were executed. Due to the restriction of Tauti's law applied to purse seine gear model test, this study modified the model criteria by introducing the shooting speed into the scale to form segmented conversion law. In the shooting process, shooting speed is the main factor determining the sinking depth and speed of the gear. After shooting, gravity and drag are the main factors controlling gear submergence in this case where Tauti's law was able to keep the similarity. The comparison of sinking depth and speed between prototype net and model net indicated that the corrected conversion law could accurately and practically applied to tuna purse seine model test.